Ernest Rutherford

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http://spcpchemroom9.blogspot.com/2010/07/ernest-rutherford.html

1)The above model, completed by Rutherford in 1911 after the experiment (below), shows a nucleus in the center (black) and electrons (red) surrounding it in a planet-like orbit. According to our packet, after the legendary gold-foil experiment (below), "Rutherford calculated that the atom was mostly space occupied by electrons and its mass is concentrated in a tiny core that he called the nucleus."

2) An experiment in 1909 completed by two of Rutherford's lab workers (Hans Geiger and Ernest Marsden) gave way to the development of this atomic model. In this experiment, a beam of alpha particles was fired at a piece of extremely thin metal foil. Rutherford concluded that because the "alpha rays" were positively charged and fast moving they would make a great probes. (basis of which to create the atomic model). (http://www.daviddarling.info/encyclopedia/R/Rutherfords_experiment_and_atomic_model.html) This experiment would be historically know as the gold-foil experiment.

3) The flaw that Rutherford had with his model was that as the model only contained positive charges. The problem with these positively charged electrons was that the electrons were always gaining speed. This is due to the fact that the electrons were always changing directions as they moved in their orbits. Since Maxwell’s time there was already proof that the accelerating charges radiate energy. The electrons would only last about one hundred-millionth of a second before they died and went into the nucleus. (http://www.daviddarling.info/encyclopedia/R/Rutherfords_experiment_and_atomic_model.html)